1. Field of the Invention
The invention relates to a buffer, and more particularly to a buffer generating an output signal comprising at least two falling slopes.
2. Description of the Related Art
FIG. 1A is a schematic diagram of a conventional display system. The display system 100 comprises a gate driver 110. The gate driver 110 provides a gate pulse GP to the pixel units P121˜P12n via the gate line 131. When the panel size of the display system 100 becomes larger, the length of the gate line 131 becomes longer. Thus, equivalent impedance of the gate line 131 is increased.
When the gate driver 110 provides the gate pulse GP to the pixel units P121˜P12n via the gate line 131, the signals of the pixel electrodes of some pixel units (e.g. P121 and P122) closed to the gate driver 110 are different from the signals of the pixel electrodes of some pixel units (e.g. P12n far away from the gate driver 110.
FIG. 1B is a schematic diagram of a relationship between the gate pulse GP and the signals of the pixel electrodes. The symbol PEnear represents a signal of a pixel electrode of one pixel unit closed to the gate driver 110. The symbol PEfar represents a signal of a pixel electrode of one pixel unit far away from the gate driver 110. As shown in FIG. 1B, the equivalent impedance of the gate line 131 causes level drift in the signals of the pixel electrodes. For example, the signal PEnear comprises the voltage difference ΔV1, and the signal PEfar comprises the voltage difference ΔV2. Since the voltage difference ΔV1 is different from the voltage difference ΔV2, the voltage differences ΔV1 and ΔV2 cannot be simultaneously compensated.